1. Field of the Invention
The present invention relates to a head coil arrangement for a magnetic resonance device, of the type having a housing on or in which a number of coils are arranged.
2. Description of the Prior Art
Head coil arrangements of the above type are known and are used in magnetic resonance devices as radio-frequency transmitting and receiving coils. If the coils operate in a receiving mode, the size of the coils in relation to the size of the test object plays a decisive role in the resulting signal-to-noise ratio. The signal-to-noise ratio is optimal if the coils rest as close as possible to the surface of the examination object, in this case the head.
In the prior art various head coil arrangements are known that are constructed so as to be suitable for at least 95% of all head sizes. By taking account of patient comfort and noise-protection, in particular by allowing space for headphones, a relatively large internal diameter results for the head coil arrangement. This is particularly the case when heads in a stereotaxic frame are to be enclosed by the coils. The head coil arrangement is therefore disadvantageously too large for some of the heads that are to be examined, resulting in a large spacing of the individual coils from the test object, i.e. the head, and therefore a poor signal-to-noise ratio.
In particular when developing new head coil arrangements with a relatively large number of individual coils the known construction is problematical due to the multiplication of the receiving channels, since the required individual coils become smaller and an improved signal-to-noise ratio is therefore indispensable in order to attain sufficiently good signal quality.